ATLAS - 15X Repair Information

Gentlemen,
This is the 15 to 160 model with power supply. I had it fixed by a ham twice and now it has failed again. I am looking for someone else who is qualified to fix it. Receive and CW works but transmit audio went out again. I am guessing but a more rugged transistor should probably be installed. wonder if anyone else has had this problem of the auto transmit going out all the time. CW output is OK.
73's